The increase in smog and other impurities in the air in most urban areas coupled with the presence of various types of allergies such as pollen and dust has resulted in the increased need for periodically treating the eyes with various ophthalmic products designed to relieve the discomforts caused by these impurities. In addition, changing consumer life styles have placed an additional strain on eyes; often requiring some kind of relief. For example, activities such as extended viewing of television, driving, close work such as sewing and needlework cause eye strain while outdoor activities where sun and/or wind are involved such as skiing, tennis, golf and sailing cause eye discomfort while activites such as swimming, surfing and smoking are considered more eye irritating. All of the foregoing place an added strain on normal functioning eyes and oftentimes require some kind of relief. Today, there are many over-the-counter ophthalmic products available for temporary relief of these irritations.
In view of the foregoing it is no surprise that recently there has been a substantial growth in the eye hygiene category; particularly in the cosmetic products available. These products have advertising positionings that emphasize "get-the-red-out", soothe and/or cleanse the eyes. Additionally, prescription products available for treating various conditions ranging from infection to diseases have increased significantly.
In the treatment of eyes with either cosmetic products or prescriptive preparations it is imperative that the product dispensed into the eye or occular cavity be sterile. With today's advanced production technology, the production and filling of sterile, ophthalmic products is fairly straight foward. With the sophisticated quality control techniques available today it is most unlikely that a contaminated product would become available to the consumer. However, after these products are filled, distributed and purchased by the consumer there is a substantial risk of their being contaminated during use. For example, in many dispensers available today contamination can result from contaminants in the air being drawn into the dispenser after some product has been dispensed. Such contaminants can then come into contact with the product remaining in the dispenser. This exchange of potentially contaminated air for the product dispensed is one of the factors that has necessitated the use of various preservative additives found in most ophthalmic products today. Such preservatives are described in Table I below and include substances such as disodium edetate, benzalkonium chloride, disodium ethylene diamine tetraacetate and thimerosal. Although these substances are generally used in minute concentrations, ranging from between about 0.001 and about 0.1% by weight; have excellent properties of inhibiting microorganism growth, and produce little known adverse side effects to the eye, it is desirable not to use them.
The presence of these preservatives even at these minute concentrations as well as the presence of the contaminants drawn into the dispenser are particularly troublesome when it becomes necessary to introduce substantial concentrations of the product into the occular cavity. Ironically, the presence of these preservatives and/or contaminants can be most troublesome when the opthalmic product is needed most and used most frequently and/or in high concentrations such as when irrigants, lubricants, miotic neutralizers and antibiotics are used.
That is, the frequent introduction of such "foreign" preservatives and dust, inactivated microorganisms or other contaminants into the eye places an additional burden on the organ necessitating: a high threshold for these substances, flushing of the substance from the eye and/or accommodating these foreign substances. It has been shown that such foreign materials are particularly burdensome to those eyes which are in a weakened condition and require periodic treatment.
Most dispensers in use today for eye hygiene have the general configuration of eye droppers which are held above the eye and squeezed to dispense the drop into the occular cavity. The instructions for their use generally include:
a. tilt the head back, PA0 b. locate dropper over eye, PA0 c. squeeze one or two drops in each eye, PA0 d. blink once or twice, and PA0 e. replace cap on dropper after use.
The traditional design of these types of dispensers includes some form of an elongated point or tip dropper means. It has now been established through extensive consumer research that this dropper design creates a basic hesitancy and oftentimes a fear for the safety of the eye in the mind of the user. This fear is referred by these researchers as the "sharp-stick-in-the-eye" syndrome. This syndrome evidences itself by a general reluctance to use ophthalmic products and/or by an ineptitude in dispensing the product into the eye.
The very nature of many eye problems requiring treatment is that when the eye is to be treated vision is often blurred or impaired. This makes dispensing even more difficult, particularly in locating an eye dropper close to the eye without touching it. If the eye is infected or contagious, contamination of the eye dropper as a result of physically contacting the area being treated becomes a primary concern.
The concern today for ophthalmic dispenser contamination caused by contacting the dropper with foreign substances is paramount. For example, almost without exception the ophthalmic products dispensed by an eye dropper type dispenser in use today, whether over-the-counter or prescriptive, contain the following type of cautionary statement: "Do not touch bottle tip to any surface since this may contaminate the solution". Because of the high risk of contact contamination most manufacturers of ophthalmic products include various preservatives in the product to inhibit the growth of such contaminants. Preservatives similar to those discussed above are generally preferred. Experience has shown that physical contact will probably be made by the dispenser with the contagious area being treated or some other source of contamination at some time during the life of the product.
The difficulty in routinely locating the dropper tip at the right distance from the eye accurately after one eye has been treated is further complicated by the general tendency of most consumers to involuntarily flinch when a drop makes contact with the eye. In fact it is often common, that if more than one drop is administered to the eye at a time, difficulty is experienced in locating the dropper for the second and following drops. The latter will often fall on the eyelid rather than the eye due to a flinching, squinting or other types of involuntary responsive reactions and the failure to locate the dropper accurately.
It has also been observed when conventional squeeze bottledropper type dispensers are used to dispense products into the occular cavity a partial vacuum is created in the dispenser after the product is dispensed. As a result, when compressive force is released from the head of the dropper or the force against the container wall is released, a charge of air enters into the container through the dispensing orifice to replace the product dispensed, thereby equalizing the pressure differential within the container. At this time, if the dropper tip is allowed to remain in the area of the occular cavity it has been observed that various loose contaminants on the skin in the area of the eye can be drawn into the dispensing orifice, eventually contaminating the liquid which is dispensed through the orifice.
Thus, as a result of this air transfer through the dispensing orifice, the internal portion of the dropper tip orifice is generally exposed to contaminants including those generally found in the air, such as bacteria/dust etc., and/or those picked up from contacting the skin around the occular cavity, or those loose contaminants drawn into the container.
In addition to the foregoing, the potential for product contamination during use is further increased by the very mechanical design of most ophthalmic dispensers in use today. That is, the dropper nozzle can be from about less than 1 to about 3 inches long. Most dropper-bottles have a dispensing nozzle from between about 1/2 to 1 inch long. When product is squeezed into the dispensing nozzle only a small portion of that forced into the nozzle is actually dispensed. The remainder returns to the container proper for dispensing at a later time. When in the nozzle, the product has an opportunity to pick up contaminants in the nozzle or at the dispensing orifice. Thus, product dispensed picks up those contaminants present and transfers them to the occular cavity, while product not dispensed picks upon contaminants within the nozzle and returns them to the main solution, contaminating it. A further possibility is that only a portion of a drop is released into the occular cavity while the remainder returns to the main solution, carrying with it contaminants picked up directly from the occular cavity.